[tex]1\,a=100\,m^2\\\\P_{\square}=a^2\\P_{\square}=100^2\\P_{\square}=10\,000\,m^2\\\\\frac{10\,0\not0\not0}{1\not0\not0}\,m^2=\boxed{100\,a}[/tex]
100m * 100 m = 10000m²
1 ar = 100m²
x = 10000m²
100x = 10000
x = 100
100 ar
